Cornwall was never formally incorporated into the English state, yet suffers the ignominy of a subordinate ‘county’ of England

‘The concept of the Duchy (Duchy of Cornwall) rests on the existence of a separate and ancient territory of Cornwall. That separate territory has never been assimilated formally into England’.

His Honor Judge Paul Laity, Recorder,

Truro Crown Court (1989)

Ancient Duchy Charters acknowledge Cornwall as a place extra-territorial to England subject to its own tax-raising powers.  Exemptions exist because, in law, the English summons of exchequer does not apply to the leader of Cornwall (Duke of Cornwall) and the territory under his command.

This situation is outlined in the third Duchy Charter in ‘Letters Patent’ Royal Command:

We have granted to the Duke [of Cornwall] that he forever have the Summons of the Exchequer of Us or Our Heirs, so that no sheriff, bailiff or Minister of Us or Our Heirs enter those fees to execute said summonses, or do any other official act [officium] there except in default of the Dukes of the said place.

(3rd Duchy Charter, January 1338)

Further to the 3rd Duchy Charter, Sir George Harrision explained:
A careful examination of the 3rd Duchy Charter shows that all remaining Crown rights were transferred to the Duke (of Cornwall).  The Crown of England therefore has entirely denuded itself of any remnant of sovereign authority which it once enjoyed in Cornwall.   Duchy Attorney General Sir George Harrison, 1857.